1. Field of the Invention
The disclosure generally relates to an electrophotographic toner and a method of preparing the electrophotographic toner.
2. Description of the Related Art
Developers for visualizing electrostatic images and electrostatic latent images in electrographic and electrostatic processes may be classified into two-component developers and one-component developers. Two-component developers include toner and carrier particles whereas one-component developers consist exclusively of toner. One-component developers can be further classified into magnetic and nonmagnetic developers. In order to increase the fluidity of toner, nonmagnetic one-component developers often contain a fluidizing agent, such as colloidal silica. Typically, toner also includes coloring particles obtained by dispersing a colorant, such as carbon black, or other additives, in latex.
Methods for preparing toner include pulverization and polymerization processes. For pulverization processes, toner is obtained by melting and mixing a synthetic resin with a colorant, and optionally, other additives. After pulverizing, this mixture undergoes sorting until the particles of the desired size are obtained. In contrast, polymerization processes provide toner by uniformly dissolving or dispersing various additives, such as a colorant, a polymerization initiator and, optionally, a cross-linking agent and an antistatic agent, in a polymerizable monomer. The polymerizable monomer composition is then dispersed in an aqueous dispersive medium, which includes a dispersion stabilizer, using an agitator to shape minute liquid droplet particles. The temperature of the composition is subsequently increased, and suspension polymerization is performed to obtain polymerized toner having coloring polymer particles of the desired size.
Conventionally, toner used in an imaging apparatus is obtained by pulverization. However, for pulverization processes it is difficult to precisely control the particle size, geometric size distribution, and the structure of toner. Thus, it is difficult to control the major characteristics of toner, such as charging characteristics, fixability, flowability, and preservation characteristics using these processes.
Recently, the use of polymerized toner has increased due to the simpler manufacturing process, which does not require sorting the particles, and the ease of controlling the size of the particles. When toner is prepared through a polymerization process, polymerized toner having a desired particle size and particle size distribution can be obtained without pulverizing or sorting. In order to control the particle size and shape of toner to be uniform in a polymerization process, an agglomeration process for preparing agglomerated toner may be used through the use of a metal salt such as MgCl2, and the like, or a polymeric material such as polyaluminum chloride (PAC).
By using a metal salt-based agglomerating agent it is possible to control the particle size and particle size distribution of toner or to reproducibly form a capsule structure with a shell. Typically, the particle size above a middle point of the particle size distribution of toner is highly controllable, however, smaller toner particles below the middle point of the particle size distribution tend to be more spherical than desired, and may cause problems in blade cleaning during electrophotographic processes. When PAC is used, the particle size and shape of toner can be uniformly controlled and toner has a stronger agglomerating force. The use of aluminum substances however, is restricted due to their effects on the environment.